Floating tank roof



1952 J. H. WIGGINS 2,606,684

FLOATING TANK -ROOF 3 Sheets-Sheet 2 I Filed Dec. 6, 1948 FIGJZ.

INVENTOR; JOHN H. W/GG/NS,

/V KW ATTORNEY Aug. .1952 J. H. WIGGINS FLOATING TANK ROOF Filed Dec. 6, 1948 3 Sheets-Sheet 3 A INVENTOR;

JOHN H. W/GG/Ns k M A TTORNEY Patented Aug. 12, 1952 UNITED STATES PATENT OFFICE 2,606,684 FLOATING TANK ROOF John Hi'Wiggins, Chicago 111 Application'December 6, 1948, Serial No. 63,791

3 Claims.

Thi invention relates to floating tank roofs, and has for its main object to provide a floating roof, which is of such design or construction that large quantities of air cannot become trapped between the underside of the roof and the liquid on which the roof floats, and thus cause rapid and destructive corrosion of the metal plates of which the liquid contacting portion of the roof is constructed in instances where the stored liquid consists of sour or highly corrosive crude oil.

Another object is to attain the result above referred to, without increasing the quantity of metal used in the roof, or increasing the cost of building the roof.

To this end I have devised a floating tank roof, which, briefly described, consists of the following elements, to wit: (a) a bottom portion constructed from a limber metal diaphragm having radially-disposed, downwardly-sagged portions that constitute air circulating passageways on the underside of the bottom of the roof extending radially from the center of same, which provide for the escape of air that collects at the surface of the liquid on which the roof floats, thereby eliminating the possibility of air becoming trapped on the underside of the roof; (1)) a top portion formed by a metal diaphgram that is arranged in superimposed, spaced relation with said bottom diaphrgam so as to serve as a rain and snow shield for same; and (c) a means in terposed between and engaged with said top and bottom diaphragm for stiffening the roof and for causing the top diaphragm to act as a weight or load which exerts a downward thrust or force on the downwardly-sagged portions of the bottom diaphragm, and thus prevents said portions from flexing upwardly when the roof is floating on the liquid in the tank.

Figure 1 of the drawings is a fragmentary radial sectional view of a floating tank roof constructed in accordance with my invention, and composed of a top diaphragm and a bottom diaphragm arranged in spaced, superimposed relationship, and attached at their peripheral edges to an annular member which constitutes the peripheral wall of a large circular pontoon, said view being taken on the line i-l of Figure 1 Figure 1 is a fragmentary top plan view of the roof shown in Figure 1.

Figure 1 is a vertical segmental sectional view of the roof shown in Figure 1, taken on the line 1 -1 of Figure 1 Figure 2 is a fragmentary vertical sectional View of a roof embodying my invention and composed of a circular center pontoon and anouter 2 annular pontoon which surrounds said center pontoon, said View being taken on the section line 2-2 of Figure 3. i

Figure 3 is a fragmentary top plan view of the roof illustrated in Figure 2, with the top diaphragm of the roof broken away, so as to show the structure between the top and bottom diaphragms of the roof that is relied upon to impart strength and stiffness to the roof and to maintain the radially fluted form of the bottom diaphragm of the roof.

Figure 4 is a fragmentary radial sectional view, taken on approximately line 44 of Figure 3.

Figures 5 and 6 are vertical sectional views, taken on the lines 5-5 and 6--6, respectively, of Figure 3. Figure '7 is an enlarged sectional view, taken on the line T-'! of Figure 3.

Figure 8 is a fragmentary top plan viewof the erection framing on which the bottom diaphragm of the roof is fabricated. I

Figure 9 is a fragmentary radial sectional view of said erection framing, with the roof shown in broken lines; and V Figure 10 is a fragmentary radial sectional view, showing the roof partially completed and supported at key points by posts or uprights after the erection framing has been dismantled or torn down.

In the drawings which illustrate the preferred form of my invention, A designates a tank that is adapted to hold liquid which is protected from the air by a roof that floats on said liquid, B designates the bottom portion or bottom,diaphragm of my improved floating tank roof, 0 designates the top portion or top diaphragm of the roof, which is in spaced relation with said bottom portion, and D designates an annular member, preferably of girder construction, attached to the peripheral edges of the topand bottom portions of the roof, so asto form a rim that projects upwardly around the edge of the bottom portion B; any preferred type of sealing structure may be used to close the annular space between the side wall of the tank and the rim D of the roof.

My improved roof is distinguished from floating tank roofs of conventional construction in two principal respects, as follows:

7(1) The diaphragm which constitutes the bottom portion or liquid contacting portion B of the roof is fabricated in such a way that it comprises radially-disposed flutes or corrugations on the underside of same whicheifectively prevent; air from becoming trapped between the underside-of the roof and the liquid when the roof is floating;

and

(2) A structure is interposed between the two diaphragms constituting the top and bottom portions C and B, respectively, of the roof, so as to impart stiffness to the roof and also to hold the bottom diaphragm against flexing and maintain it in a radially-fluted or corrugated condition, So far as my broad idea is concerned, any preferred procedure or method may be gused in fabricating or combining'the co-acting parts ofthe roof and producing the radially-disposed flutes or corrugations on the underside of the bottom diaphragm, and any suitable type or kind of structure may be used between the top and bottom diaphragms of the roof to stifienitherroof and to prevent the fluted bottom portionpf the roof from flexing out of shape when the roof is floating. The bottom portion of the roof consists of a circular diaphragm B, made up of metal plates that are preferably fabricated or connected together in such ;a way as f to produce a continuous limber diaphragmthat-has aslight downwardpitch from-itsperipheral edge towards itscenter, Said diaphragm-may forlnthe bottomsof -:a large circular, pontoon of only slightly less diameter than the tank in which I the roof is rused, or it-mayform the! bottom-ofa circular center ,pontoonand -one-- or more annular pontoonsarrangedin concentric -relation-with said center pontoon. The top portion C 1ofthe roof may be of anypreferredconstruction, so-long as it is of considerable weight and is :of .-s,uch shap orsferm :that i s-W ;-i:ns r srap.id;and-se cientidrainage of rain or n w .thatfa ls. ent r roof.

:I ha e ,hereini illustrated sai op portion C as consisting of a diaphragm thatcomprises an a ul -s ape periphenalrnoittl n W G 1S1 P downwardly I and inwardly from A ,the *rim ;D :to :a collection trough E onthetop surface of: thereof, and a conershaped c,entral- -portion that slopes outwardly and downwardly towards said -:col-lec tion trough E. The structure that-is :used to stiffen the roof and also to maintain thetfluted shape -01" form of the bottom v'diaphragm of the roof, :consists :of radiallyedisposed trusses and vertical hold-down struts, arranged between the top and bottom diaphragm C and B of the:roof, and rigidly attachedto-said' bottom diaphragm. Usually, said trusses-and hold-down strutswill be held in engagement with the top diaphragm of the roof, due to the friction producedby the weight-or load ofsaid-top diaphragm, .but if desired, the top diaphragm -of the roof can be welded {or attached in any otherpreferred manner-to-said trusses and'hold-downstruts. Preferably, the procedure'of-building the roofinvolves fabricating the bottom diaphragm=B from metal plates that are joined together many preferred manner-so asto produce a continuous, limber sheet then causing radially-disposed portions of said diaphragm to sag downwardly, subsequently, combining the previously Ementioned radial tIUSSBSWlthrSBid bottom; diaphragm, so that said trusses hold certainrradii of the bottom diaphragm:ima-strei ht l newandi st n the parts of said'diaphragm lyingbetween the downwardly-sagged portions of the diaphragm, then 'fabricatingthe ,top diaphragm-G of the roofwhile the ,metal- :plates constitutingsaid diaphragm areresti-ng upon .or supported by the abovementionedradial trusses, and thereafter interposing the previously. mentioned hold-down struts between the .topdiaphragm C andbottom sagged;-portio ns of the bottom diaphragm B, and

attachthe hold-down struts to the top sides of the valley-like portions formed by the downwardly-sagged portions of said diaphragm.

{The roof shown in Figures 1, 1 and 1 is constructed in the form of a large circular pontoon of onlyslightly less diameter than the tank A.

AsshowninFigure l the bottom portion of said pontoonis formed by a diaphragm B, which is pIQYidQd With radially-disposed flutes or corrugations that form air circulating passageways on the .undersideof -the bottom ,of the roof, wh n th r o -isfio tin .A r v l Stated, and as shown in .l igurev 1, the d aphra m vB is pitched downwardly slightly from its .peripheral edge towards the center of the dia phragm, and. consequently. the radially-disposed flutes in the diaphragmB have a slight upward pitch from the center towards the peripheral edgeof the roof, thereby increasingthe tendency of the air to-flow outwardly towards therim or outer edge portion of the roof. A trussing structure that is arranged onthe interiorofthe roof, ,in engagement with-:the ,top and bottom diaphragmsof same, imparts suflici-ent. stiffness to the roof to enable the roof to successfully carry anabnorma rai --.or.-snowi oad. :1 ha herein illustr ted. said-pu sies ,stru turease mp is szor bein .eompos dzof top-cord members ien a ed with theinnderside ofrthe topplenhrasm C,;a d exte di g radially from the, c nter frthe ro fztotherim:D,;as'.-sl1own inb oken lines;in -l5?igpre 1 vertical,-tr-ussgmembers ,2 attached to said radial top-cords l and to the top side of the -.bottom diaphragm B, and inclined braces 3 attached to said above mentioned parts, as shownin'F-iguregl. Bybuilding the roof in this manner, I reduce the cost and weightof the roof and. simplify the construction of same, due to the fact thatthe bottom diaphragm'IB serves as the bottom cords ofradially-disposed trusses which are relied upon-to stiffen the roof and hold certainradiiof the bottom diaphragm of the roof-in a-str aight line. Preferably-as shown in Figure 1 the above mentioned radially-disposed trusses arearranged in longitudinal alignment with theridges-x of theuflutes in the bottom diaphragm B that form air circulating passageways on the underside of the roof, when the roof is floating. The flutedor corrugatedshape or condition'of the bottom diaphragm B is maintained-by a 'meansor structure interposed between thetopand ,bottom portions of the roof and illustrated herein as being composed of or comprising vertical hold-down struts 4 interposed between the top diaphragm C and bottom diaphragm;l3,.and arranged in spaced relation alongthe valley-like portions in the top faceof the bottom diaphragm B formed by the downwardly-sagged portionsrof said bottom diaphragm. Usually, circumferentiallysdis posed supporting members?) for the toppdiaphragm C of the roof will be. attaohedto the top cord members I, so as to bridge the spaces between said top ,cordmembers, and the upper ends of the hold- .down struts4 willrbe attached ure 1 to said supporting members 5, as shown in Fig- In a roof of the construction above described, the internal structure interposed between and engaged with the top diaphragm C and bottom diaphragm B, effectively trusses the roof from one side to the other and holds the bottom diaphragm of the roof in such shape or form that certain radii of said bottom diaphragm are held rigid in a straight line, and downwardlysagged portions of the bottom diaphragm lying between said radii are prevented from fiexing upwardly when the roof is floating. In such a roof the downwardly-sagged portions of the bottom diaphragm form flute-like air circulating passageways on the underside of the roof which gradually increase in width from the center towards the peripheral edge of the roof, the ridges of saidflute-like air circulating passageways be ing held in a rigid condition by the radially-disposed trusses attached to the top side of the bottom diaphragm. The previously mentioned annular water collection trough in the top surface of the roof is herein illustrated as being formed by an annular member positioned between the oppositely-inclined drainage surface on the top side of the roof and welded or permanently attached in any other way, to the metal plates, which form the cone-shaped central top side of the roof and the downwardly-pitched, peripheral part at the periphery of the top diaphragm C of the roof. As is obvious, suitable outlet drains 6 are provided for the annular collection trough E, and the top portion C of the roof will be equipped with numerous manholes (not shown) that provide access to the interior of the roof during the building of same, and when the roof is in use.

In Figure 2 of the drawings I have illustrated a roof that embodies the novel characteristics and features of the roof shown in Figure l, but which is distinguished from same, in that instead of being constructed in the form of a single large pontoon, it is composed of a circular center pontoon that constitutes a large portion of the area of the roof, and an annular peripheral pontoon that surrounds and is attached to said center pontoon, the bottom portion B of the roof being formed by a circular, radially-fluted diaphragm of the kind previously described, which constitutes the bottom of both of the above mentioned pontoons. In the roof shown in Figure 2, a second annular member D, preferably of girder construction, set inwardly some distance from the rim D of the roof in concentric relation with same, is interposed between and attached to the top and bottom portions C and B of the roof, so as to separate the central portion of the interior of the roof from the peripheral portion of the interior. As shown in the drawings, the annular member which constitutes the bottom of the drainage trough E is attached to the web of said second annular member D, so as to form, in effect, the top flange of an annular girder. The top cord members I in the center pontoon terminate at the girder D, but the bottom diaphragm B of the roof extends outwardly to the peripheral girder that constitutes the rim D of the roof. The interior of the peripheral pontoon, formed by the two annular girders D and D and the peripheral parts of the top and bottom portions of the roof attached to said girders, is divided into a plurality of compartments by radiallydisposed bulkheads 1, arranged preferably in longitudinal alignment with the cord members I. The compartments of the peripheral annular 6 pontoon located between the bulkheads I are provided with radially-disposed rafters 8 that support the top walls of said compartments, and

ing or deformation of the bottom diaphragm B adjacent the rim of the roof.

The co-acting parts of the roof may be assembled or connected together by any preferred procedure or method. One simple method that I have devised involves the following procedure, to wit: Forming the bottom portion B of the roof from metal plates that are joined together so as to produce a substantially dish-shaped or inverted cone-shaped diaphragm, causing or permitting radially-disposed portions of said diaphragm to sag downwardly so as to impart a radially-fluted shape or form to the diaphragm, attaching radially-disposed trusses or truss members to the top side of the diaphragm at points between the downwardly-sagged portions of the diaphragm so as to stiffen and hold certain radii of the diaphragm in a straight line, such, for example, as the top cords I and vertical truss members 2, previously referred to, fabricating the top portion C of the roof from metal plates supported by and engaged with the top cord members on the underside of the top portion of the roof, and attaching the top and bottom portions C of the roof to an annular member that constitutes the peripheral rim of the roof, as shown in Figure l, or attaching the top and bottom portions of the roof to an annular rim, and to a second annular member set some distance inwardly from the rim, as in the roof shown in Figure 2. In Figures 8, 9 and 10 of the drawings I have illustrated in detail the preferred procedure of construction the roof shown in Figure 2. Preparatory to starting the fabrication of the bottom diaphragm B, I build an erection framing in the tank A on the bottom of the tank, said framing being composed of two groups of radially-disposed rafters l2 and I3 supported by uprights or legs I4, as shown in Figures 8 and 9, the rafters l2 and i3 being pitched downwardly slightly from the tank side wall to the center of the tank, as shown in Figure 9. Metal plates are then laid on said erection framing and joined together, so as to produce a continuous limber diaphragm, Whose central portion is pitched downwardly slightly from its peripheral edge, Certain of said radially-disposed rafters are then removed, such, for example, as the rafters l3, shown in Figure 8, with the result that radially-disposed portions of the diaphragm which lie between the rafters 12 will sag downwardly. Subsequently, in any preferred sequence, the members that constitute the outer and inner girders D and D are attached to the diaphragm B that rests on the erection framing formed by the rafters l2 and the previously-described radial trusses, bulkheads and holddown struts are attached by welding or in any other suitable manner to the top face of said diaphragm B, thus producing a supporting structure on which the plates constituting the top portion C of the roof can be laid while said plates are being joined together. If desired, prior to fabricating the top portion C of the roof, while it is supported by the previously described trusses, bulkheads and holddown struts, the erection framing on which the bottom diaphragm of the roof was fabricated can be dismantled or removed progressively and rea e by le sor vertioal uprights L4,; shown in Figure 10, that supportthe partially completed ,roof atkey points as'for example, at the-peripheral edgeof the roof at thecenter of the roof, and at; the inner circular: girder D.

, InFigure 1 and FigureB of the drawings, the

arrows indicate the direction of flow ofthe air ,oorgaseswhich collect on the ,undersideof the roof, the arrows in Figure -3 ,being in broken lines.

Having thus describedmy invention, WhatI claim as new and desire to ,secure hyLe-tters Pat- ,ent is:

1. A;-flo ating tank roof, comprisingia metal diaphragm that constitutes the bottom-portion of the roof, at top diaphragm arranged inspaced relation-e with said, bottom diaphragm, said loot t m d phra m in r ia -di o flute or -corrugations that form air circulating passageways on the undersideof the roof-Whenthe roof isfloating, radial trusses arranged-in spaoed relation between said diaphragms and attached to the-top sides'of thevridges of the-flutes in the bottom. -di aphragm to; stifi;en;the same, and holddown struts -on-the interior of the roof interrposed between saidt topand bottom diaphragms for pausing- ;part of-the Weight or load of the top diaphragm to exert a downward force on the .--portions of the bottom d-iaphragm intermediate isai'dxtrus e s as t preven upw r ex n ,said intermediate portions.

:2.. A-pfloa ine-tani: roof, compris n antan u metal diaphragm that constitutes the bottom of h r o a. roo o t rort on-a ra i 'sn relation w thaidwb tt m diap ra m an annula rim of circular oonstruotion attached to the pa ern d e hr em an t th op part'of t e roofat'the-peripheral edges of same, the bottom diaphragm being provided with downwardlysag ged portions that form flutes or corrugations on the underside of said bottom diaphragm which extend re diall-y from the center of said-diaphragm towards the periphery of same, trussing members entire-interior of the-roof attached-t0 the ,top

flutessoas. to cause the top part of the/motto act,;as, .a lojad or downward force thatis applied ito the, ,downwardlyrsagged portions of the bottom. diaphragm.

,3.,A floating tank roo,f,,.comprising. a top portio-n,and a bottom ;-.portion. arranged in spaced superimposedirelation, an annular rim attached to the peripheraledges of said top andbottom porti n stifl radial trusses between thetopand bottomportions of the root attached .to certain radiiof the bottom portion located between downwardlyrsagged parts of said bottom portion, and members on the interior of theroofinterposed betweeniand engaged with the top portion of the roof and the downwardly-.sagged parts of the bottom;p.ortio-n for causing the/top portion of the roof to function as a weightv or load that exerts adownwardthrust on} the sagged portions and thuspreventsaid sagged portions from flexing upwardly, the bottom portion of the roof vbeing pitched, downwardly slightly from its peripheral edge towards its center.

' JOHN, .VVIGGIDIS.

REFERENQES QI'IYED The following references. are of recordin ,the

file of this patent:

UNITEDSTATES PATENTS Number Name Date 1,748,231 Kimbell Feb. 25, 1930 1,815,124 Patterson July 28, 1931 2,355,874 Laird Aug. 15, l944 2,460,053 Wiggins Jan. 25, 1949 2,464,786 Allen Mar. 22. 1949 

